"SIMI VALLEY, Calif. -- Lingering radioactive contamination exists at a former rocket test lab outside of Los Angeles that was the site of a partial nuclear meltdown, federal environmental regulators said Wednesday."

"The Environmental Protection Agency launched a $42 million study to investigate radioactive pollution at the Santa Susana Field Laboratory, 25 miles northwest of downtown Los Angeles.

Technicians collected 3,735 soil samples from a corner of the 2,850-acre hilltop lab where most of the testing was done. Of those, they found about 10 percent contained radioactive concentrations exceeding background levels.

Most of the contaminated soil was found in places like the materials handling facility that were previously cleaned, but it looked like "isolated spots were missed," said Mary Aycock, an EPA Superfund remedial project manager."